The invention relates to a method for depositing on an edible supporting material .alpha.-L-aspartyl-L-phenylalanine-methyl ester having a particle size that is in the main smaller than 100 .mu.m, by mixing the .alpha.-L-aspartyl-L-phenylalanine-methyl ester and the supporting material in a dry form.
Such a method is known from JP-B-93007983. This Japanese patent describes that fine, powdered .alpha.-L-aspartyl-L-phenylalanine-methyl ester (which compound will hereinafter also be referred to as aspartame or as APM) can be homogeneously deposited on the surface of granular sucrose (cane sugar) by mixing the APM and the granular cane sugar. As is apparent from this patent, the APM and granular cane sugar to be used must have particle sizes of less than 100 .mu.m (APM) and in the range of 0.01 to 3 mm (cane sugar), respectively.
The method is however absolutely unsuitable for depositing more than 10 wt. % APM on the cane sugar and is preferably recommended for making products that contain only 0.5 to 5 wt. % APM. In the case of higher APM concentrations in the compositions obtained, a considerable proportion of the APM remains in the composition in a free form. This may be detrimental to the composition's homogeneity and flow properties, which is expressed in a poor angle of repose, and it may also cause dusting problems. Excessive adhesion of APM particles to the walls of the equipment employed and/or packaging materials is also frequently encountered and free APM particles may agglomerate, which has an adverse effect on the dissolution time of the APM in the composition obtained.
.alpha.-L-Aspartyl-L-phenylalanine-methyl ester (aspartame; APM) is a dipeptide sweetener with a sweetening power that is about 200.times. that of sugar. Aspartame is widely used as a sweetener in a wide diversity of edible products, soft drinks, confectionery, medicines and in table sweeteners and the like. APM is often used in the form of dry blends, such as instant powdered drinks and instant dessert products and the like.
The use of APM (and/or of blends thereof with a different sweetener), in particular of powdered APM, is often hampered in terms of handling by the fact that the products in question are insufficiently free of dust (i.e. they contain too many fines), show poor flow behaviour (which may be partly caused by slight electrostatic charging of the products), or have a relatively long dissolution time, for example owing to the formation of agglomerates. Consequently, drawbacks are often experienced in the use of APM in terms of dusting behaviour, undesired adhesion to surfaces of the equipment employed and poor dissolution time of the APM.
To reduce those problems in, for example, the foodstuffs industry efforts have been made to find methods for transforming APM and edible supporting materials (for example citric acid, maltodextrins, etc.) into compositions. According to the above-referenced Japanese paten application, its method proves to be more or less limited in terms of the APM concentrations realisable in the composition (generally to at most 5 wt. %, but to 10 wt. % at the very most). Besides the method from the aforesaid Japanese patent publication, no simple methods for preparing such compositions, or compositions having higher APM concentrations, which do not involve auxiliaries, for example wetting agents, or laborious process steps, have been described or are otherwise known. For example, several publications are known in which compositions of APM and other substances are prepared, also with APM concentrations that are higher than 10 wt. %. According to several of such publications, the greater part of the APM in the resulting product is however not deposited on the supporting material, and hence usually less than 50 wt. % of the APM, but often even less than 15 wt. % of the APM, is bound to the surface of the supporting material, and/or the method involves the use of additives or laborious steps. The following methods can be quoted as examples:
spray drying, or spraying the supporting material with a concentrated APM solution, followed by drying (ZA-9205142); PA1 freeze-drying (U.S. Pat. No. 3,922,369); PA1 mixing with wetting, followed by drying (U.S. Pat. No. 5,114,726); PA1 mixing in the presence of binders, with wetting, followed by drying (JP-A-59059173); PA1 so-called `high-shear mixing`, also known as micro-mixing, i.e. mixing with a high energy input and pulverising conditions (JP-B-89016142); this patent describes that the APM may be homogeneously distributed among the other component or a part thereof, optionally before the high-shear treatment, by mixing in for example a tumbler mixer (becoming surrounded by particles of the other material in the process, so to speak), so as to prevent agglomeration of the APM; however, in this method the APM is certainly not deposited on supporting material, but a physical powder blend is obtained; in spite of claims to the contrary in this patent, segregation problems, etc. remain inherent; PA1 grinding of a blend to obtain a mixed product with a homogeneous particle size distribution (p.s.d.) (NL-A-7404428).
Such methods often require specific equipment or special process control devices and laborious steps and/or steps involving extra risks of decomposition of the thermally relatively sensitive APM. Mixing with high energy input is usually disadvantageous, not only because of the dusting and drifting problems presented by the end products obtained, but also because of the energy consumption involved. Neither do a number of the above methods result in advantages in terms of reduction in the adhesion of the APM to walls and the like.
There is hence a need for a simple and efficient method for converting APM and edible supporting materials, via mixing involving little energy, into a composition in which all or a sufficient amount of the APM, or almost all, that is, at least 50% (a sufficient amount), but preferably at least 85% (almost all), is deposited on the supporting material in amounts that may clearly exceed 10 wt. %, resulting in a homogeneous product with good dissolution and handling properties. It is assumed to be particularly advantageous if the method in question can also be carried out under very dry conditions, for example at a relative humidity of 70% or lower, or using very dry, non-hygroscopic supporting materials.